160 likes | 186 Views
Explore the differential effects in the butter market using multivariate regression, analyzing Danish and New Zealand butter prices in the British market from 1930 to 1936. Test hypotheses on regression coefficients and relations between prices and quantities.
E N D
Multivariate Regression British Butter Price and Quantities from Denmark and New Zealand 1930-1936 I. Hilfer (1938). “Differential Effect in the Butter Market,” Econometrica, Vol. 6, #3, pp.270-284
Data • Time Horizon: Monthly 3/1930-10/1936 • Response Variables: • Y1≡ Price of Danish Butter (Inflation Adjusted) • Y2≡ Price of New Zealand Butter (Inflation Adjusted) • Predictor Variables: • X1≡ Danish Imports • X2≡ New Zealand/Australia Imports • X3≡ All Other Imports
p Responses k Predictors n observations Multivariate Regression Model
Least Squares Estimates Note: This assumes independence across months
Butter Price Example • p=2 Response Variables (Danish, NZ Prices) • k=3 Predictors (Danish, NZ, Other Imports) • n=80 Months of Data • First and last 4 months (x0 is used for intercept term):
Testing Hypotheses Regarding b • Many times we have theories to be tested regarding regression coefficients • The most basic is that none of the predictors are related to any of the responses • Others may be that the regression coefficients for one or more predictor(s) is same for two or more responses • Others may be that the effects of two or more predictors are the same for one or more response(s) • Tests can be written in the form of H0: LbM = d for specific matrices L,M,d
Testing for a Differential Effect • Hypothesis: Price of Danish and NZ Butter is equally “effected” by quantities of each type • H1: Common Effects for each quantity / price, common intercepts • H2: Common Effects for each quantity / price, different intercepts • H3: Common Effects for quantities, different effects across prices • H4: Differential Effects for quantities, common effects across prices
H and E Matrices Note: F.05,6,75=2.22, F.05,5,75=2.34, F.05,4,150=2.44, F.05,4,75=2.49 All 4 hypotheses are rejected